This application claims the priority of German Patent Application 102 13 656.6 filed Mar. 27, 2002 and entitled xe2x80x9cFastening Device For Child Seat On A Motor Vehicle Seatxe2x80x9d by Michael Haverkamp, the entire contents and substance of which are hereby incorporated in total by reference.
The invention relates to a fastening device for a child seat on a motor vehicle seat.
Restraint systems for child seats located on a motor vehicle seat are known in many embodiments. In earlier times it was customary to utilize herefor the safety belt system of the vehicles which was present in the vehicle anyway. However, such systems bear the disadvantage that the connection between the child seat and the vehicle seat may loosen over time due to the flexibility of both upholstery and belt, allowing the child seat some movement on its own. Therefore, in recent years systems are in use, in which the holders for the child seat are rigidly connected to the structure of the seat or the vehicle. Such systems have become known to the experts as xe2x80x9cIsofixxe2x80x9d child seat fasteners. Due to the rigid connection such fasteners are not subject to loosening, so that own movement of the child seat, as discussed above, is essentially impossible.
However, even with xe2x80x9cIsofixxe2x80x9d fasteners a child seat may not be prevented from pivoting forward through the resilience of the upholstery in the case of strong braking deceleration forces occuring, for example, in the event of a front crash. This pivoting motion may lead to injury in the cervical spine of a child sitting in the child seat, commonly referred to as cervical trauma. Of course, this danger also exists with other types of fasteners of child seats.
In order to overcome this danger so-called xe2x80x9ctop tethersxe2x80x9d have been developed. Top tethers are restraining means connecting the upper part of the back mould of a child seat with rear fasteners affixed to the vehicle or to the motor vehicle seat. Such a generic fastening device was described in DE 298 20 475 U1. In one embodiment of the invention disclosed in the aforementioned citation the fastening device consists of two hook shaped fastening means held at the upper front side of the back mould of the child seat. The free ends of the hooks can be removably inserted into the guides of a head rest fastener following the prior removal of the head rest from these guides. In another embodiment of the invention cited belts are used instead of hook shaped fastening means, and buckles are provided at the ends of such belts which can be inserted into buckle tongues. These buckle tongues are penetrated by the carrier arms of the head rest. In a further embodiment of the invention cited the belts are replaced by rods, one end of which is pivotingly affixed to the upper front side of the back mould of the child seat with the other end being provided with an aperture which is in turn penetrated by a holding rod of the head rest.
A fastening device similar to the one described above has been described in DE 201 17 074 U1. Herein, the fastening device consists of a fixing belt affixed to the back side of the head rest of the child seat. Said fixing belt is designed so as to consist of two parts and is provided at each of its two free ends with a buckle or a buckle tongue respectively by means of which the fixing belt can be closed in a known manner. In order to fasten the upper region of the child seat, the two ends of the fixing belt are manipulated around the holder rods of the head rest of the motor vehicle seat and joint via the belt buckle. The length of the belt loop can be shortened by pulling one end of the belt in a known manner until the fixing belt is in form-fit contact with the holder rods.
In these known solutions the holding means of the head rest of the motor vehicle seat, i.e. the guides and/or the holders, are utilized directly for fixing the upper region of the child seat.
Safety regulations of some countries prescribe certain requirements for the fastening location of the xe2x80x9ctop tetherxe2x80x9d, whereby these requirements depend upon certain seat related reference points. The solutions described above are unsuitable for meeting such demands because the respective fastening region lies too close to the reference points.
WO 01/36226 A2 discloses a system for anchoring objects at or on a motor vehicle seat. One embodiment of this system relates also to the fastening of a child seat on a motor vehicle seat. Besides an xe2x80x9cIsofixxe2x80x9d fastener in the lower region of the child seat there is provided a xe2x80x9ctop tetherxe2x80x9d conncetion. The belt used herein as holding means is affixed at its one end to the upper side of the back mould of the child seat and at its other end bound to a holder ring which is in turn affixed to a structural part of the passenger compartment of the vehicle. This solution is capable of meeting the above safety requirements because the location of fixation of the end of the holder belt which faces away from the back mould can be designed to be spaced sufficiently away from the seat reference points. However, this solution is not suited for front seats because there are no sufficient corresponding fixation points of the support structure of the passenger compartment available in the front. A further disadvantage can be seen in that the structure of the passenger compartment must have sufficient rigidity at the point of fixation of the holding belt in order to withstand the forced excerted during a front crash. This demand may not always be met, for example, in the case of the parcel shelf behind the back seat of a passenger sedan.
The present invention is based upon the object of providing a fastening device of the generic type which can be used independently of the location where a vehicle seat is mounted inside a passenger compartment and, moreover, provides a fastening point for a so-caclled xe2x80x9ctop tetherxe2x80x9d sufficiently located towards the back meeting the requirements of applicable safety regulations.
Thus, the fastening device according to the invention can be inserted, with its first region, into the guides for the head rest provided in the upper region of the back rest of the motor vehicle seat after removal of the head rest from these guides. The further region of the fastening device then protrudes towards the back so that the fastening point provided here is located sufficiently towards the back, i.e. that the distance from the relevant seat reference points prescribed by applicable safety regulations can be met. While in the state of the art the head rest holders or their guides respectively serve directly as fixation points for the holding means connected to the upper region of the back mould, in the present invention the head rest guides are utilized merely indirectly in that they serve as fixations for the fastening device at the back rest. The fastening device according to the invention can be used both with front as well as back seats.